Railway signaling system.



A. v. T. DAY. RAILWAY SIGNALING SYSTEM.

APPLICATION FILED AUG. 28, 1908.

1,125,488, Patented Jan.19,1915.

UITE

ALBERT V. '1. DAY, OF NEW ROCHELLE, NEW

YORK, ASSIGNOR, BY MESNE AESSIGN- MENTS, TO HALL SWITCH & SIGNAL OMPANY, OF NEW YORK, N. YL, A CORPORATION or Mama.

- 55 i. BAILVVAY SILENALING SYSTEM.

Patented Jan, is, isle,

Application filed August 28, 1908. Serial No. 450,715. I

had therein to the accompanying drawings,

forming part. thereof.

' My invention relates to electric trafficcontrolling systems and apparatus for railwa *s, and the object of the invention, generally stated, is to produce a traffic-controlling system which shall be simple and re-' liable in construction and operation.

VVhile my invention is applicable, in general, to systems of various kinds, for the 'operation'of various traflic-controlling devices,

such as automatic train-stopping devices, switches, der-ailing switches, and the like, it is particularly ap'plicabl'e'to automatic systems for controlling visual signals, such as semaphores, and I have illustrated and particularly described my invention as applied to such a signal system.

It has heretofore been proposed to use traflic-contrblling systems in which the track railsare employed as conductors in signalcontrolling circuits and are .fed at differentv points with alternating or other periodic currents of different frequencies. These currents are used to actuate relays, which control the signals, and each of the severalrelays is made responsive only to current of one frequency, so as to be actuated "only by rom a given feeding point current flowing 1 or polnts 1n the rails. This arrangement s 'designedto operate in such amanner, that each relay is controlled by the presence or absence of a trainin or near the portion of the track connecting the relay with the point from which the appropriatecurrent flows, the train, when present, acting to shortcircuit either the relay or thcsource of current so as to deenergize the relay in so far as the current of the particular frequency necessary for actuating the relay is con-- cerned.

In the system above referred to, it has been proposed to supply given frequency at the several different feed ing points through a transmission a common generator, and to derive the cur rent. at these-points-thmugh suitable transthe current of a line from formers.v This arrangement is defective for the reason that where current is derived at different points on the track from a common conductor, this conductor may act, under certain circumstances, as a conductor for stray currents from other sources, with the result that current of a given frequency may be conducted and fed to points in the rails where it is intended to be absent, so that signal-controlling relay may be improperly actuated by current from an unintended source at a time when its normal source is out off and the relay should be deenerg-ized. This defect relates particularly to the several relay-actuating currents, and is such that withthe above described arrangements each transformer, in addition to feeding the current of proper frequency, may also feed to the rails more or less of each of the other currents of different frequencies used in the system, so that current appropriate to any relay may be found at any point in the rails.

My invention is applicable to a system having the general character of that just described, and one object of the invention is to obviate, in such a system, the objectionable feature above referred to. To this end I provide an independent source of current for each of the several feeding points in the rails. The several sources of current may be generators, and they may be and preferably are, driven by power derived from a common source in such a manner as to synchronize their operation and simplify the construction of the systemfbut electrically these generators are wholly independ ent of each other and of the transmission line, so that. the arrangement affords no path for the transmission of stray currents. In the system hereinbefore referred to each relay is rendered selectively responsive to current of the appropriate frequency by providing it with a magnetic field energized by current of the same frequency, derived. from the same source as the current in the rails intended to actuate the relav. In order that a relay so individualized may operate in an entirely reliable manner it is necessary to guard absolutely against the encannot be done in the arrangement above referred to, and under certain circumstances a. relay may therefore become more or less responsiveto currentsfrom sources other sources wholly independent of the sources.

from. which are derived the currents fedrto I the rails.

In the system hereinbefore referred to," when alternating or-other periodic current .18 used for traction purposes, the track rails 7 serving as a return conductor therefon the traction current is necessarily of a difi'erent frequency, from that'of any of the relays actuating currents,

direct interference of the traction current Withfl the signal-controlling system.

Indirectly, however, even a traction current of substantially different frequency may interfere with the proper operation of the relays. In case there arises, from any cause such as a broken rail or bond, a sub stantial difference of potential in the track rails due to the traction current, traction current will flow into the transmission lines and into the fields of the relays, thereby rendering the relays responsive to traction current, and a portion of the traction current,

flowing through the armature coils of therelays from therails, at improper times.

An object of my invention is to avoid this defective operation, and this result is accommay actuate the relays plished by energizing the fields of the relays .from'sources wholly disconnected from the track rails, so that no possible path is afforded for traction current from the rails to the fields of the relays.

Otherobjects and features of my invention will be set forth in connection with the description of the embodiment of my invention illustrated in the accompanying drawings.

I will now describe the illustrated em-- bodiment of my invention, and will thereafter point out my invention in claims.

The-drawing illustrates diagrammatically a portion of an electric signal-controlling system.

The track rails 25 and 26. constitute the westbound track of a double-track railroad,-

the trains moving from right to left, as indicated by the arrows '1. The track is divided into blocks by signals 2, although the track rails are bonded or otherwise rendered continuously conductive throughout the system. The signals are located each at the entrance end'of a block, While the signal-controlling relays are located approximately at the middle of each block.

In the following description a signal with its controlling relays and the means for'energizing the track rails at the entrance end ofthe block, are considered as constituting a signal station and in the drawings the several signal stations are designated sucthese frequencies occur but in the following description the letters B, etc. are sometimes added to the refer ence numbers, when it is necessary to indicate at which station any one of such'similar parts islocated.

Each signal2 is controlled by two track relays 3 and 4.. The relay 3 is of the polar- 'iz'ed periodic current type. It has a field magnet 5 and a pivoted armature 6 proyided with a coil and carrying a contact finin Q order toavoid .8. The relay 4; is in all respects similar in construction, and has a contact finger 9 and a' 'fixedcontact 10. The construction of these relays is such that when the field magnet'and the coil carried by'the armature are energized by periodic currents of the same frequency andof proper phase relation the contact finger is held in engagement with the fixed contact, thereby closing the circuit controlled by the relay while 'under any other circumstances the contact finger falls and opens the circuit.

The armature coils of each pair of track relays 3 and 4 are connected in parallel by wires 11, across' the track rails at points designated bythe numbers 12, 13, 14, etc.

so that both relays are energized by all the currents in the rails. Each relay is responsive, however, only to current of a certain frequency, and the relays of each pair respond to currents of diflerent frequency. The field coil 5 of the relay 3 is connected by wires 18, with transmission wires 21 fed by an alternating-current generator 24-, while the field coil of the relay 4* is similarly connected with and energized by a generaton 22. These generators are designed to produce currents of substantially different frequency, and these two frequencies are for convenience, indicated by the letters 0 and a in the drawings, these letters being applied at various points where or are efi'ectiveto operate the apparatus.

The object in making the relays 3 and 4 responsive to currents of different frequencies is to make the relay 3 responsive only to current from the block, and the relay 4 responsive only to current from the western half of the block. The eastern half of the block A is fed, at a point 27 by current of 0 frequency, by analternating current generator 34. This generator is driven by mechanical connection with an electric motor 35, whlch is of eastern half of the Lies em .one wire each of the transmission lines nating and constant currents is merely an expedient of convenience and economy as an independent line might be used for the constant current.

"The current of a frequency fed at the point 27 to the rails is normally transmit ted through the rails to the point 12 and the armatures of the track relays at A; and it actuates the relay 3, causing it to hold its contact finger 7 against its fixed contact 8. i

The western'half of the block is fed at a point 28 by current of a frequency, from a generator 34 similar to the generator, above described, at station A, except that the generator B is constructed to generate current of a frequency. The current fed at the point 28 is normally transmitted through the rails toithe point 12 and the arlnatures of the relays 3 and 4 and it actuates the relay 1, causing it to hold its contact finger 9 against its fixed contact 10.

The signal 2 and its electrically-controlled actuating mechanism are not particularly illustrated, as they may be of any ordinary or suitable construction. The signal has a bias to danger position, but is maintained in clear position When its actuating mechanism is thrown into' operation by the closing of the signal circuit.

The si nal circuit be innin at the si 'nal- D a D D 2*, passes through a Wire 53, to the contact finger 9 of the relay 4%, thence, through the fixed contact 10 and a Wire 50, to the contact finger 7 of therelay 3 thence, through the fixed contact 8, to the signal battery 51, and thence, by a Wire 52, to the signal again. This circuit "is normally held closed by the relays 3 and 4:, and the signal is,

normally held in clear position.

Since the current of a'frequency fed at the point 28 travels in both directions through the rails the relay 3 is made responsive to current of this frequency by connecting its field *"ith the transmission wires 19. The relay 4 is made responsive to current of a third frequency, 7), by connecting its field with the transmission Wires 20, which are fed by a generator 23 similar to the generators 22 and 2a. The current to energize the armature of the relay. 4 flows from the point 29 at the western end of the block, where it is supplied by a generator 34 similar, except for the frequency of the current generated. to the generators Mat A and B.

At station A the arrangement of the relays is such that the armature coil of each relay receives current not only of the fre quency to which it is sensitive, but also currents of other frequencies flowim z in the rails, so that it acts to some extent as a short circuit for currents by which other.

relays are to be actuated. This does not interfere With the operation of the system Where the resistance of the armature coils is suiiicien't to reduce the shoit-circuiti-ng action to a negligible amount, but this action may be substantially prevented by the arrangement-of apparatus illustrated at stations B and C. Herestepnp 'transfermers are used between therails and'the re lays, and between each relay and the trans former is a condenser 56tuned in resonance with the field of the corresponding relay,

so that each relay armature coil receives only current of the appropriate frequency, the condenser acting" to exclude currents of other frequencies. l

' The frequencies a, Z) and 0 are used at the successive feeding points throughout the line, in the same order 2'. 0., c, a, b, a, a, 6, etc. The arrangement of the relays and the signal circuits may be precisely the same at all the signal'stations and the two track relays at each station are arranged to be responsive to the currents from the feeding points at the eastern and Western ends, respectively, of the corresponding block.

.' All of the track generators 34 of each particular frequency are connected with the two track rails in.the same sense, so that there is normally no flow of current there-- from except through the armature coils of the relays.

With the apparatus in normal condition, suppose a. car or a train enters the eastern half of the block A, so as to occupy a position between the points 12 and 27 on the track. The Wheels and axles of the train connect the two rails electrically, and the current from the point 27 normally flowing to the relays 3 and 4c is thus short-circuited. The armature of the relay 3* is thereupon substantially deprived of current of c frequency, and the contact finger 7 falls, thereby opening the signal circuit and permitting the signal 2 to go to danger position behind the train. It is true that unde these circumstances the armature of the relay 3 is not Wholly deprived of current of c frequency, since (iurrent of this character may be transmitted from the feeding point 30,

and from other points farther in advance, but as these points are two and one half blocks or more in advance of the point 12, the current transmitted is reduced to a negligible amount by the impedance of the intervening length of rails, and the relay may be readily adjusted so as not to respond to a current so faint.

When the train reaches the middle of the block it short circuits both relay armatures, thereby doubly opening the signalcircuit.

NV hen the train-is in thcavestern half of the block it intercepts the current a frequency flowing from the point -28 and thereby causes the relay 4 to keep the signal circuit lqperii until the train arrives at-theend of the loc The feeding points 27,28, etc, while 10- cated appronimatelyv at the entrance ends of. each block, are, in each case, situated a short distance to the west of the corresponding signal. As a train advances toward a feedand if the feeding point were located at the signal the signal would go to danger positrain reached it intion shortly before the stead .of during or afterthe passing of the train. The westerly displacement of the feeding points is provided to *avoid this faulty operation, and the amount of displacement required is determined by" the sensitiveness ofthe relays, the impedance of the rails, andother causes which may be made sufliciently definite for practical purposes. J

In-order to prevent direct interference of the traction current with the signal system, the traction generator is constructed to give current of a frequency substantially different from the frequencies a, b, and c. This frequency is indicated by the letter d.

It will be apparent that as all of the track generators 34 are wholly independent from each other and from the transmission lines by which the fields of the relays are cue! gized, there are no paths afiorded for stray currents either from point to point on the track 'or from a point on the track to the field of a relay. The possibility of improperoperation-ansing from such stray currents in" the ways hereinbefore referred to is therefore wholly precluded- A further advantage of the arrangement of the motors and generators illustrated at B, and C lies in the fact that the phase of the current delivered by a generator 84 may be adjusted by turning the armature of the generator upon the shaft by which it is I connected'with the motor 35. This feature is of value in compensating for the difference in the respective impedances of the paths over which the alternating currents must pass in reaching the same point. Thus, for example, each relay is designed to be actuated by alternating currents of the same frequency and of definite phase relation in its armature coilund it's field coil. The cur; rent in the'field coil derived from a transinission line, while the current in the armature coil is derived from a generator located at a distance-and "is transmitted through a track circuit having an impedance which is a ing the generator armature upon its shaft so as to'give the current from the generator sufiicient lead to compensate for the impedance of the track circuit.

While I have, for the sake of simplicity in illustration, shown-and 'described a system in Which'lonly .home signals are employed, the invention is equally applicable,

to a system arranged in anyusual or suitable manner to control .both home and distant signals. 1 v p I The currents of different frequencies used to control the. relays selectively need not necessarily. be three in number. Two such currents, 'fed alternately t0 the rails, will sufice, but three currents are considered, for some reasons, preferable, and in some cases it may be preferable to use four or more.

Various modifications may be made in the embodiment of my invention hereinbefore particularly described and illustrated in the accompanying drawings Within the nature of the invention and the scope of the following claims.

A I claim:

1. A railway traflic-controlling system comprising track rails, means for feeding periodic currents of different frequencies at different points in the rails, traffic-controlling devices, relays for controlling the trafficcontrolling devices, a plurality of the relays being connected with the rails at substantially the same point, and means interposed 4 between a relay and the rails to exclude from the relay currents of other frequencies than that to which the relay should'respond. 2. A railway trailic-controlling system comprising track-rails, means for feeding periodic currents of different frequencies at.

different points in the rails, traffic-controlling devices, relays for controlling the trafficcontrolling devices, a plurality of the relays being connected with the rails at substantially the same point, and resonance devices interposed between the relays and the rails to exclude from each relay currents of frequencies other than those, to which :they should respond. v I

3. A railwaytraffic-controlling system comprising track rails, means for feeding periodic currents of difie'rent frequencies at dilferent points in the rails, a traffic-controlling device, a relay controlling the trafficcontrolling device, connectedto the track rails, and selectively responsive .to:current of a given frequency in the rails, and resonat1ng-current the track rails to propel the at intervals, motors arranged generators, .a circuit for supplying the motor armatures, a separate cirgenerators arranged to feed cuitfor supplying arate generators tor supplying said separate circuits. v

Inltestimony whereof I have aflixed my signature in presence of two Witnesses.

' ALBERT V..' T. DAY.

Witnesses:

FARNUM F. D RsEY,

'WM. ASHLEY KELLY.

topics of this patent may be obtained for fiveeents each, by adciressing; the Gommissi oner of Patents,

' Washington, D. G.

the motor fields, and sep- 10 Q 

